Heat exchanger



Sept. 6, 1955 HEAT EXCHANGER Filed March 10, 1952 W. L. SHOULDERS ET AL 5 Sheets-Sheet l IN V EN TORS ROBERT R. HAYES 8 By WALTER L SHOULDERS v/zw w ffig p 6, 1955 w. L. SHOULDERS ET AL 2,717,320

HEAT EXCHANGER 3 Sheets-Sheet 2 Filed March 10, 1952 INVENTORS ROBERT E. l-MYES 8 y WALTER L. SHOULDERS WM w Sept. 1955 w. L. SHOULDERS ET AL 2,717,320

HEAT EXCHANGER Filed March 10, 1952 5 Sheets-Sheet 3 INVENTORS ROBERT HAYES a y WALTER L. SHOULDERS United States Patent HEAT EXCHAN GER Walter L. Shoulders and Robert R. Hayes, Cleveland, Ohio, assignors to Reliance Electric and Engineering Company Application March 10, 1952, Serial No. 275,812

6 Claims. (Cl. 31057) The invention relates in general to heat exchangers and more particularly to gas-to-gas heat exchangers for use with an explosion-proof frame of a dynamoelectric machine.

The heat exchanger of this invention is particularly adaptable to an explosion-proof frame wherein air or 1 gas from the inside of an enclosed frame is circulated through a closed duct external of the frame with this duct having a multitude of internal metal fins to absorb the heat from the air. The internal metal fins are carried internally by a ring or annular member which forms the duct and a plurality of these duct sections are used. These duct sections may be substantially identical and a plurality of them may be stacked to give ducts of different lengths. The individual duct sections also have a multitude of external fins so that the heat may be passed to these fins and may be given off to the surrounding atmosphere. To improve the heat transfer, the duct is preferably enclosed with a shroud and a stream of air is directed within the shroud past these external fins. Any convenient form of blower arrangement may be used which circulates the air within the frame and within the duct and a second blower is preferably used to direct air past the external fins. Accordingly, it is an object of the invention to provide a heat exchanger for an explosion-proof motor or generator wherein a gas is circulated within the frame and within a closed duct external of the frame.

Another object of the invention is to provide a heat exchanger having a duct for passage of air or gas with this duct made of a plurality of substantially identical duct sections which may be stacked to obtain any desired length.

Another object of the invention is to provide a duct for a heat exchanger composed of a plurality of substantially identical duct sections, each of which has a multitude of internal fins as well as external fins.

Another object of the invention is to provide a heat exchanger made of a plurality of duct sections, each of which has substantially parallel external fins and each of which has a plurality of sectors of internal fins with each sector having substantially parallel fins.

Still another object of the invention is to provide a heat exchanger for an explosion-proof frame of a dynamoelectric machine wherein a first blower is used to circulate air within the frame and the explosion-proof duct and a second blower is used to direct air externally of said duct with both blowers operating from the same shaft.

Other objects and a fuller understanding of this invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a side elevational view of a dynamoelectric machine having a heat exchanger mounted thereon with the heat exchanger shown in section;

Figure 2 is a rear elevational view of the complete motor and heat exchanger;

Figure 3 is a front elevational view of the motor and heat exchanger;

Figure 4 is an elevational view of one of the duct sections; and

Figure 5 is a section on the line 55 of Figure 4.

The Figures 1, 2 and 3 show the general arrangement of a dynamoelectric machine 11 with a complete heat exchanger 12. This heat exchanger is shown with a large machine 11 and comprises in this embodiment a first complete duct 13 and a second complete duct 14. A shroud 15 is used to house these two complete ducts 13 and 14, however it will be obvious that two separate shrouds may be used. The Figure 1 is a section taken through the first complete duct 13 and since the ducts 13 and 14 are identical, only one will be explained.

The machine 11 has a frame 16, a base 17, a shaft 18, and on the front end bell, has first and second openings 19 and 243, respectively. The rear end bell of the machine also has first and second openings 21 and 22. The first and second openings are disposed at an acute angle of approximately 45 degrees relative to each other in a plane perpendicular to the shaft 18. The first openings 19 and 21 cooperate with the first complete duct 13 and the second openings and 22 cooperate with the second complete duct 14. Each of the complete ducts 13 and 14 includes a first duct end 23 and a second duct end 24. These duct ends have first portions 25 and 26 and have second portions 27 and 28. Between the first and second portions, there is a right-angle bend so that the second portions 27 and 23 extend toward one another and define a longi tudinal axis 29 which is parallel to the shaft 13. Each of the duct ends is generally circular in cross-section and on the second portions thereof, there is a female fitting 30.

A plurality of identical first duct sections 31 are used between the duct ends 23 and 24. These first duct sections 31 are better shown in Figures 4 and 5, These duct sections have a shorter axial length than diameter and on one end, each has a female fitting 34 and each has on the other end a male fitting 35. An adapter duct section 36 has a male fitting 37 on both ends thereof so that the complete duct 13 includes the duct ends 23 and 24, a plurality of first duct sections 31, and an adapter duct section 36, all mated together.

The duct sections and duct ends are preferably made from a metal which has a good heat conductivity. Aluminum is a suitable metal and it is easily worked. The various parts of the duct may be cast from aluminum and then the necessary machining performed on these parts. The Figures 4 and 5 show one of the first duct sections 31 and this includes a ring 40 on opposite ends of which are the female and male fittings 34 and 35. These fittings may be turned on a machine tool so that close tolerances may be obtained to provide a closed duct 13 which has flame-proof fits incident to an explosion-proof motor. Another application of the motor and duct would be a dirt-proof seal for dirty atmospheres to prevent the dirt or fumes entering the interior of the motor. The duct sections 31 have internal fins 41 and external fins 42. The internal fins 41 are divided into four sectors of degrees each. In each sector, the fins 41 are parallel and of varying length. The middle fin in each sector is the longest and extends directly toward the longitudinal axis 29. The internal fins extend generally toward the center of the duct and tereminate just short of the dividing line between sectors. The external fins 42 are parallel and the ends of these fins form a heptagon with the base of the heptagon being the longest side and adapted to lie adjacent to the frame 16 of the machine 11. The two sides of. the heptagon adjacent the base are disposed at an acute angle of about 45 degrees so that the two complete ducts 1'3 and 14 may lie adjacent each other at approximately this same 45 degree angle therebetween. Theentire duct section 31'may be cast for this purpose, the ring 49, as well as the fins 41 and-42, may have aslight taper along the axial length of the section so that it may be removed from the mold.

The second duct end 24 may also be cast from aluminum and this duct end includes internal director, fins 43. These fins help curve the path of the air circulating through the duct. The duct end 24 also has external fins 44 and, as better seen in Figure 3, there are fewer external fins on the duct end 24 than on the duct sections 31. Sincethere are fewer internal fins in the duct end 24 to collect the heat, fewer external finsare needed thereon to dissipate this heat. The duct end 24- also has bosses 45 with longitudinal apertures 4". The duct end 23 also hasexternal fins 47 similar to the fins 44 and preferably cast as an integral part of. this duct end. The ductend 23.also has internal director fins 48 which in this case are made from separate pieces of metal, such as stamped sheet metal. These fins-t3 are held in place by suitable rods 49. The duct end 23 has a blower motor frameSQin which is housed an electric blower motor 51. This motor 51 has a shaft 52 generally along the axis axis 29. This shaft 52 is journaled in a bearing 53 and sealed at this point in a wall of the duct end 23. A director hub 54 is carried by the adapter duct section 36 and this hub carries a bearing 58 which journals the other end of theshaft 52. The shaft 52 has fastened thereto an axial fiow fan or blower 59. The hub Sdis carried in the adapter duct section 36 by curved director fins 60. These fins curve the flow of-air so that the blower 59 may operate more efiiciently.

Curved director fins 61 are provided externally of the frame 50 and again curve the flow of air so that a sec ond axial flow fan 62 may operate efficiently. This fan 62 is fixed to the external end of the shaft 52 and is used to direct a stream of air pastthe external fins 61, 47, 4?. and 44: The shroud 1.5 closely engages the ends of all of the external fins intheir generally heptagonal shape and assures that the flow of air from the fan 62 passes between these external fins. Eosses 69' are provided on the motor frame 5t; and'have a threaded aperture therein to receive long bolts 7f). These bolts '75 extend through the longitudinal apertures M in the second duct ends 24; Nuts 71 are threaded on the ends of these bolts and are used to hold the duct sections and duct ends together to make the flame-proof complete duct T3 or 14. An electrical junction box 65 is mounted on the machine 11 and is usedto provide electrical connection to the two separate electric blower motors 5'1. A plate 66 closes off the underside of the heat exchanger to contain the external air within the shroud 15. This shroud 15 has a forward open end 67 and a rear open end 68 generally along the longitudinal axis 29.

Suitable switch controls may be provided for the blower motor 51 and when the machine 11 is operating and giving off heat, the heat exchanger 12 would preferably be placed in operation in order to dissipate this heat and hence increase the effective rating of this machine. The axial flow fan 59 will circulate a flow of air or gas within the complete duct 13 and the frame 16. Of, course, the other blower motor circulates air between the. complete duct 14 and the frame 16. The heat from the air within the frame 16 is thus transferred to the internal fins 41, 43 and 48 where. it travels by. conduction to the external fins 42, Maud 47 and there is dissipated by the fiow of air caused by the fan 62. A single complete duct may be used as a heat exchanger in which case, the shroud would preferably lie close to the ends of the-external fins, This embodiment shows two complete ducts which have been paralleled for this. particular size machine. Because of the included angles of the sides of the heptagon adjacent the base being at a 45-degree angle, this means that any plurality of complete ducts may be paralleled around the periphery of the machine 11 with three, four or more ducts being feasible in order to achieve the necessary heat dissipation for any application. Further, the complete ducts may be varied in length by removing or adding duct sections 31 so that the heat exchanger may be used with motors or generators of different lengths. Perhaps only two or three duct sections would be necessary with a small size machine, whereas ten or a dozen duct sections could be used with larger machines, this combined withv a plurality of completed ducts in parallel.

Although this invention has been described in its preferred form with a.certain degreeof particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from thespirit and the scope of the invention ashereinafter claimed.

What is claimed is:

l. A heat exchanger for apparatus emitting heat and having a frame with an opening near each end including, first and second duct ends, said duct ends having a bend between first and second portions thereof, said first portions being mountable on said frame openings and said second portions establishing a longitudinal axis, said secend portions extending toward one another andeach having a female fitting on a circular opening therein, a plurality of substantially identical duct sections each having a male and a female fitting on opposite ends of a circular opening therein; an adapter duct section having a male fitting on both ends of a circular opening therein, said plurality of identical duct sections and said adapter duct section mating together and mating with the second portions of said duct ends to form a closed duct between said frame openings external of said frame, each of said substantially identical duct sections being formed as a ring to define the said circular opening and having internal and external fins extending from said ring, said internal fis being defined by a plurality of groups in each of which the fins are substantially parallel, said external fins all lying substantially parallel and terminating in the form of a polygon, means to fasten together said duct ends and said duct sections to form a flame-proof closed duct, said first duct end having a shaft aperture substantially on the longitudinal axis thereof, ashaft extending through said shaft aperture from the exterior to the interior of said closed duct, a first blower mounted on said shaft inside said closed duct to circulate air, within said closed duct and said frame, a shroud open at both ends and enclosing and lying close to the external fins, and a second blower external of said first duct end and arranged to direct a stream of air within said shroud and between said external fins.

2. A heatexchanger for a frame of a dynamoelectric machine with a shaft axis, said frame having an opening near each end,- said heat exchanger including, first and second duct ends, said ductends having a bend between first and second portions thereof, said first portions being mountable on said frame openingsand said second portions establishing a longitudinal axis, said second portions extending toward one another andieach having a female fitting on a circular opening therein, aplurality of sub stantially identical duct sections each having a male and a female fitting'on opposite ends of a circular opening therein, anadapter duct section having a male fitting on both endsof a circular opening therein, said plurality of identical duct sections and said adapter duct section mating together and mating with the second portions of said ductends-to form aclosed duct between said frame openings, each of said substantially identical duct sections being formed as a ring to define the said circular opening and having internal and external fins extending from said ring, said internal fins being defined by a plurality of substantially identical sectors, each sector having substantially parallel internal fins of varying length extending generally toward the center of said ring, said external fins all lying substantially parallel and terminating in the form of a heptagon, bolt means to fasten together said duct ends and said duct sections to form a flame-proof closed duct, an electric blower motor carried by said first duct end, said first duct end having a shaft aperture on the longitudinal axis thereof, a shaft extending through said shaft aperture and driven by said blower motor, a shroud open at both ends and enclosing said external fins, a blower on said blower shaft external of said first duct end driven by said blower motor and arranged to direct a stream of air within said shroud and between said external fins, and a second blower mounted on said blower shaft inside said closed duct to circulate air within said closed duct and said frame.

3. A heat exchanger for a frame of a dynamoelectric machine with a shaft axis, said frame having an opening near each end with said openings having axes at an angle to said shaft axis, said heat exchanger including, first and second duct ends, said duct ends having an angular bend between first and second portions thereof, said first portions being mountable on said frame openings and said second portions establishing a longitudinal axis substan tially parallel to said shaft axis, said second portions extending toward one another and each having a female fitting on a circular opening therein, a plurality of substantially identical duct sections each having a male and a female fitting on opposite ends of a circular opening therein, an adapter duct section having a male fitting on both ends of a circular opening therein, said plurality of identical duct sections and said adapter duct sections mating together and mating with the second portions of said duct ends to form a closed duct between said frame openings, each of said duct sections being formed as a ring to define the said circular opening, said substantially identical duct sections having internal and external fins extending from said ring, external fins on said duct ends, said internal fins being defined by a plurality of substantially identical sectors, each having substantially parallel internal fins of varying length extending generally toward the center of said ring and terminating a short distance from the dividing line between sectors, said external fins all lying substantially parallel and terminating in the form of a polygon, one side of said polygon being the base formed by two oppositely extending external fins and I disposed closest adjacent said frame, the two sides of said polygon adjoining said base defining an acute angle relative to each other such that two complete heat exchangers may be paralleled on a single frame at an included angle therebetween approximately equal to said acute angle, a blower motor frame fitted to said first duct end, bolt means to fasten together said duct ends and sections and blower motor frame to form a flame-proof closed duct, an electric blower motor mounted in said blower motor frame, a shroud enclosing said external fins, a blower driven by said blower motor and arranged to direct a stream of air within said shroud and between said external fins, said first duct end having a shaft aperture on the longitudinal axis thereof, a shaft connected to said blower motor and extending through said shaft aperture from the exterior to the interior of said closed duct, and a second blower mounted on said shaft inside said closed duct to circulate air within said closed duct and said frame.

4. A heat exchanger for a frame of a dynamoelectric machine with a base thereon and a shaft axis, said frame having an opening near each end on the side thereof opposite said base with said openings having axes generally perpendicular to said shaft axis, said heat exchanger including, first and second duct ends, said duct ends having a substantially right angle bend between first and second portions thereof, said first portions being mountable on said frame openings and said second portions establishing a longitudinal axis substantially parallel to said shaft axis, said second portions extending toward one another and each having a female fitting on a circular opening therein, a plurality of substantially identical first duct sections each having a male and a female fitting on op posite ends of a circular opening therein, an adapter duct section having a male fitting on both ends of a circular opening therein, said plurality of first duct sections and said adapter duct section mating together and mating with the second portions of said duct ends to form a closed duct between said frame openings external of said frame, each of said first duct sections being formed as a ring to define the said circular opening and having internal and external fins extending from said ring, external fins on said duct ends, said internal fins being defined by four substantially identical sectors of ninety degrees each, each sector having substantially parallel internal fins of varying length extending generally toward the center of said ring and terminating a short distance from the dividing line between sectors, said external fins all lying substantially parallel and terminating in the form of a heptagon, one side of said heptagon being the base formed by two oppositely extending external fins and disposed closest adjacent said frame, the two sides of said heptagon adjoining said base defining a forty-five degree angle relative to each other such that two complete heat exchangers may be paralleled on a single frame at an included angle of approximately forty-five degrees therebetween, bosses next adjacent the outer periphery of said duct ends between said external fins, said bosses having longitudinal apertures generally parallel to said longitudinal axis, a blower motor frame fitted to said first duct end, bolt means extending through said boss apertures to fasten together said duct ends and sections and blower motor frame to form a flame-proof closed duct, an electric blower motor mounted internally in said blower motor frame, a shroud open at both ends and enclosing and lying close to the heptagonally formed external fins, a blower driven by said blower motor and arranged to direct a stream of air within said shroud and between said external fins, and a second blower driven by said blower motor inside said closed duct to circulate air within said closed duct and said machine frame.

5. A heat exchanger for a frame of a dynamoelectric machine with a shaft axis, said frame having two openings near each end with said openings having axes generally perpendicular to said shaft axis and with the axes of the openings at each end disposed at a given angle therebetween, said heat exchanger comprising, first and second paralleled ducts, each duct including first and second duct ends, said duct ends having an angular bend between first and second portions thereof, said first portions being mountable on openings as opposite ends of said frame and said second portions establishing a longitudinal axis substantially parallel to said shaft axis, said second portions extending toward one another and each having a female fitting on a circular opening therein, a plurality of identical duct sections each having a male and a female fitting on opposite ends of a circular opening therein, an adapter duct section having a male fitting on both ends of a circular opening therein, said plurality of identical duct sections and said adapter duct section mating together and mating with the second portions of said duct ends to form a closed duct between openings at opposite ends of said frame, each of said identical duct sections being formed as a ring to define the said circular opening and having internal and external fins extending from said ring, external fins on said duct ends, said internal fins being defined by a plurality of substantially identical sectors, each sector having substantially parallel internal fins of varying length extending generally toward the center of said ring and terminating a short distance from the dividing line between sectors, said external fins on each duct all lyingsubstantially parallel and terminating in the form of a polygon, one side of said polygon being the base formed by two oppositely extending external fins and disposed closest adjacent said frame, the two sides of said pol gon adjoining said base defining substantially said given angle relative to each other such thattwo complete ducts may be paralleled on said frame at substantially the same distance from said shaftaxis, bolt means to fasten together said duct ends and said'ductsections to form a fiameproof closed duct, an electric blower motor mounted internally in each of said first duct ends, and a blower driven by said blower motor inside said closed ducts to circulate air within said closed ducts and said frame.

6. gas-to-gas heat exchanger for an explosion proof dynamoelectric machine having a frame with a base there on and a shaft axis, said frame having two openings near each ad with said openings having axes generally perpendicular to said shaft axis and with the axes of the openings at each end disposed at an included angle of approxi y forty-iive degrees therebett'een, said'heat exchanger comprising, first and second parallel ducts, each duet including first and second duct ends, said duct ends having a substan i right angle bend between first and second portions there-of, said first portions being mountable on openings at opposite ends of saidframe'and said second portions establishing a longitudinal axis substantially parallel to said shaft axis, said second portions extending toward one another and each having a female fitting on a circular opening therein, a plurality of identical duct sections each having a male and a female fitting on opposite ends of a circular opening therein, er dt t section having a male fitting on both ends c' opening therein, said plurality of identical duct sections and said adapter duct section mating together mating with the second-portions of said duct ends to form a closed duct between openings at opposite ends of said frame, each of said duct sections being cast as a ring to form the said circular opening and having external fins extending from said ring, internal fins extending from said ring on said identical duct sections, external fins on said duct ends, said internal fins being defined by four substantially identical sectors of ninety degrees each, each sector having substantially parallel internal fins of varying length extending generally Lt but,

toward the center of said ring and terminating at short distance from the dividing line between sectors, said external fins on each duct all lying substantially parallel and terminating in the form of a heptagon, one side of said hep tagon being the base formed by two oppositely extending external fins and disposed closest adjacent said frame, the two sides ofsaid hepatgon adjoining said base defining a substantially forty-five degree angle relative to each other such thattwo complete ducts may be paralleled on said frame at substantially the same distance from said shaft axis and at an included angle of approximately forty-five degrees therebetween, a blower motor frame fitted to each first duct end, bosses nextad acent the outer periphery of said blower motor frame and said second duct end be tween said external fins, said bosses having longitudinal apertures generally parallel to said longitudinal axis, bolt means extending through said boss apertures to fasten together said duct ends and sections and blower motor frame to form a flame-proof closed duet, an electric blower motor mounted internally in each of said blower motor frames, said first duct ends having shaft apertures on the longitudinal axis thereof, shafts extending through said shaft apertures from said blower motors to the exterior, of said closed ducts, a blower mounted on each of said shafts inside said closed ducts to circulate air within said closed ducts and'said motor frame, said heat exchanger also comprising a shroud open at both ends and enclosing and lying close to the external fins on both said ducts, second blowers external of each of said first duct ends on said shafts and arranged to direct a stream of air within said shroud and between said external fins.

References Cited in the file of this patent UNITED STATES PATENTS 1,519,673 Doble Dec. 15, 1924 1,921,056 Walker Aug. 8, 1933 2,171,253 Day Aug. 29, 1939 2,460,957 Whitfield Feb. 8, 1949 2,529,516 Scheibel Nov. 14-, 1950 2,654,583 Treanor Oct. 6, 1953 FOREIGN PATENTS 252,791 Great Britain June 7, 1926 351,906. Great Britain Dec. 23, 1929 

